Many structural ceramic materials are finding uses in situations requiring good mechanical properties or other physical properties which can not easily be provided by other types of materials. Unfortunately, use of structural ceramic materials has been limited by their high cost.
The high cost of many structural ceramics may be partly attributed to high cost of the starting ceramic powders which are to be shaped and densified to form structural ceramic parts. The starting powders are often made by energy-intensive processes or by other expensive methods adapted to produce high purity starting powders. Generally, it has been preferred to minimize the impurity contents of the starting powders in order to maximize the performance of the ultimate ceramic part.
In some instances, ceramic materials have been prepared by reaction processing wherein the starting materials include powder reactants which are reacted to form a desired ceramic composition. The ceramic composition is then fired to obtain a densified ceramic product. Fully densified ceramics are often very difficult to obtain because the original porosity of the reaction mixture combined with a density decrease from the reaction result in a low density compact. Such low density compacts are typically very difficult to sinter to full density.
Accordingly, there is a need for inexpensive structural ceramic materials and methods of making those materials, especially if one wishes to take greater advantage of ceramic properties in commercial applications.